I would like to correct any false conclusions drawn from this incident. Omar Mateen was NOT acting in accord with true Islam. The Sharia has strict rules for, firstly, determing the guilt and, then, assigning the penalty for a practising homosexuality.
Here is the Shafi'i school of jurisprudence's discussion of the matter (emphasis by VE):
"The legal penalty is OBLIGATORILY imposed upon anyone who fornicates or commits sodomy
(PROVIDED it is legally established)
[AND] when they:
(a) have reached puberty;
(b) are sane;
(c) and commit the act voluntarily...
... IF the offender is someone with the capacity to remain chaste, THEN he or she is stoned to
death... (def: 0]2.6), someone with the capacity to
If the offender is not someone with the capacity to remain chaste, then the penalty consists of being scourged one hundred stripes."
Mr. Mateen had no evidence that any of the people he killed were practising homosexuals, or that the other conditions for a capital sentence were met.